In the ever-evolving landscape of web performance, choosing the right image format can significantly impact your site's loading speed, user experience, and SEO rankings. Two modern formats, WebP and AVIF, have emerged as strong contenders against traditional formats like JPEG and PNG. But which one should you choose for your website in 2023?

WebP vs AVIF format comparison chart

What Are WebP and AVIF?

WebP: Google's Modern Image Format

WebP is an image format developed by Google that provides superior lossless and lossy compression for images on the web. It was first announced in 2010 and has gained significant browser support over the years.

AVIF: The Next Generation Format

AVIF (AV1 Image File Format) is a relatively newer image format based on the AV1 video codec. It was developed by the Alliance for Open Media (AOMedia) and offers even better compression efficiency than WebP.

Key Takeaway

Both WebP and AVIF are modern image formats designed to replace older formats like JPEG and PNG, offering better compression and quality.

Compression Efficiency Comparison

When it comes to compression, both formats significantly outperform traditional formats, but AVIF generally has the edge:

Format Average Size Reduction vs JPEG Lossless Compression Animation Support
WebP 25-35% smaller Yes Yes
AVIF 50% smaller Yes Yes
JPEG Baseline No No
PNG Larger (lossless) Yes No

Browser Support in 2023

Browser compatibility is a crucial factor when choosing an image format for the web:

WebP Browser Support

WebP enjoys excellent browser support in 2023:

  • Chrome: Supported since 2010
  • Firefox: Supported since 2019
  • Safari: Supported since iOS 14 and macOS Big Sur (2020)
  • Edge: Supported since 2019

AVIF Browser Support

AVIF support is growing but not as universal as WebP:

  • Chrome: Supported since version 85 (2020)
  • Firefox: Supported since version 86 (2021)
  • Safari: Limited support (iOS 16+, macOS Ventura+)
  • Edge: Supported since version 90 (2021)
Pro Tip

Use the <picture> element with fallbacks to ensure compatibility across all browsers while serving modern formats to supported browsers.

Image Quality Comparison

Both WebP and AVIF maintain excellent image quality at lower file sizes compared to JPEG:

WebP Quality Characteristics

WebP provides good visual quality with minimal artifacts, especially at higher quality settings. It handles both photographic content and graphics well.

AVIF Quality Advantages

AVIF generally produces better visual quality at equivalent file sizes, with superior preservation of fine details and color accuracy. It particularly excels with complex images and gradients.

Performance Impact on SEO

Image format choice directly impacts Core Web Vitals, which are crucial for SEO:

Largest Contentful Paint (LCP)

Smaller image files load faster, improving your LCP score. AVIF's superior compression typically results in better LCP performance.

Cumulative Layout Shift (CLS)

Properly sized modern images reduce layout shifts. Both formats support proper dimension specification.

Implementation Examples

Here's how to implement both formats with fallbacks:

// HTML with picture element for format fallbacks
<picture>
  <source srcset="image.avif" type="image/avif">
  <source srcset="image.webp" type="image/webp">
  <img src="image.jpg" alt="Description" loading="lazy">
</picture>

Conversion Tools and Workflow

Converting images to modern formats is straightforward with the right tools:

WebP Conversion

  • Google's cwebp command-line tool
  • ImageMagick with WebP support
  • Online converters like Squoosh
  • Resizr's built-in WebP conversion

AVIF Conversion

  • libavif library and tools
  • ImageMagick (recent versions)
  • Squoosh.app
  • Sharp library for Node.js

Conclusion: Which Should You Choose?

For maximum compatibility today: Use WebP as your primary modern format with JPEG fallbacks. WebP offers excellent compression with near-universal browser support.

For future-proofing and best compression: Implement AVIF with WebP and JPEG fallbacks using the <picture> element. This approach delivers the best possible experience to supported browsers while maintaining compatibility.

For most websites in 2023: A combination of both formats served conditionally provides the optimal balance of performance and compatibility.

Sarah Johnson

Sarah is a senior web performance engineer with over 8 years of experience optimizing websites for Fortune 500 companies. She specializes in image optimization, Core Web Vitals, and modern web performance techniques.